A low-temperature co-fired ceramic (hereafter referred to as “LTCC”) substrate is constructed by performing conductor wiring on sheets obtained by mixing an aggregate of alumina and a glass material thereby to form a multilayer film, followed by firing the multilayer film at a temperature as low as about 800 deg. C. In terms of practical use, the LTCC substrate comprises a single mother board on which a plurality of functional areas are formed simultaneously in a lattice pattern, and the mother board is divided into separate small substrates on a functional area-by-functional area basis. Heretofore it has been customary to use a cutting tool whereby the mother board is broken into pieces by means of mechanical cutting.
Moreover, in order to achieve fragmentation of a glass substrate or the like, as disclosed in Patent Document 1, the substrate made of such a brittle material is scribed by a scribing apparatus first, and is whereafter cut into pieces along the resulting scribe lines. In this description, the term “scribing” refers to an operation to engrave scribe lines (guide lines for cutting) on a substrate made of a brittle material by rolling a scribing wheel over the substrate in a mutually pressure-contact state. The substrate formed with the scribe lines can be fragmented readily simply by causing development of a vertical crack (a crack which runs in the direction of thickness of the substrate).
[Patent Document 1] International Publication WO 2005/028172A1